williams



S. B. WILLIAMS, JR

'- TELEPHONE EXCHANGE SYSTEM Filed Dec. 28 1,920 9 Sheets-Sheet 1' fly] 5w F/y M Vania/1 Samar/6. h/il/fams/zr March 25, 1924. 1,487,996 s. B. WILLIAMS, JR

TELEPHONE EXCHANGE SYSTEM Filed Dec. 28 1920 9 Sheets-Sheet 2 //4 1 644 #014- Samue/B. M/fl/mms/n mmwem 3- M a-1i- 25, 1924. 1,487,996

S. B. WILLIAMS, JR

TELEPHONE sxmmoa SYSTEM Filed Dec. 28 1920 M van 70/4- Sam 416/ B. WWW/775 //4 Marcli 25, 1924. 1,487,996

A S. B. WILLIAMS. JR

TELEPHONE EXCHANGE SYSTEM Filed Dec. 28. 1920 v 9 Sheets-Sheet 5 March 25, 1924. 1,487,996

s. B. WILLIAMS, JR

TELEPHONE EXCHANGE SYSTEM Filed Dec. 28 1920 9 Sheets-Shec 6 //7 yer/for.

fiamz/e/ 5. [Mi/Hams (/r. b

y R. W M m/4w.

March 25, 1924.

- s. B. WlLLlAMS, JR

TELEPHONE EXCHANGE SYSTEM 9 Sheets-Sheet '7 Filed Bed. 28 1920,

' [)4 ania/4 Samua/ 6. M/Mms/K March 25, 1924; 1,487,996

' S. B. WILLIAMS, JR

TELEPHDNE EXCHANGE SYSTEM Filed Dec. 28 1920 9 Sheets-Sheet 8 MARGINAL //4 van/0n Samua/B. M/fi'ams/n .R. WW A773 March 25, 1924. 1,487,996 1 s. B. WILLIAMS, JR

TELEPHONE EXCHANGE SYSTEM Filed Dec. 28. 1920 9Sheets-Sheet 9 Wye war: Samue/fl M/l/ams/z Patented Mar. 25, 192 .2.

3331C COMPANY, IDTCQ r 'OG]ZT"1\T. n w ASSIGNOF. r0 WESTERN ELEC- ID. o. nn

0137., 1231'. Y., A CORPORATION OF NEW lIEEIlT-IEHONE-EXCHANGE SYS'IEllE.

Application filed December 28, 1920.

a citizen ot the United States, residing "ooklyn, in the county of Kings, State York. have in ited certain new id useful provements 1n 'lCtelephone- Jliauge s stems, oi? which the following is clear, concise, and exact description.

This invention relates to telephone exchange systems and more particularly to such systems in which connections between lines are established under the control of subscribers.

One of the objects of? the invention is to provide an improved automatic telephone system of the relay type.

Another object of the invention is to provide a system of this nature which will accommodate lines oi various characters, such as individual lines, party lines, and rural lines.

Still another object of the invention is to provide in a full relay automatic telephone system, involving lines of dilierent charactors, a two-way trunk circuit, with means whereby connections may be established betwecn subscribers of the system and an operator at a distant exchange.

To carry out the various objects, the invention contemplates dividing the lines terniinating at an exchange into groups, lines of various characters. such as individual lines, party lines, and rural lines being grouped indiscriminately, that is any one group may contain individual lines only, rural lines only, or party lines only, or any number of either two or all three oi the lines different character. For interconnecting 01 lines of the system relayline finders, link circuits, and relay connectors are employed. It subscdber in initiating; a call causes a group, subgroup and units controlling relay to be actuated which causes one of the line finders to connect with the calling line and thereafter extend the calling line the link circuit associated therewith. Associated with the link circuit variably operable impulse receiving device which responds to impulses received trom the calling station and a variably operable impulse recor device which records th nurahe of impu transmitted. speciacal in the p entchsclosure reiaysare employed in the Serial No. 433,665.

impulse receiving and in the impulse recording device.

Another feature of the invention consists in providing alink circuit with switching l'liGijllzlnlSll'l for connecting one of a plurality of sources of ringing current thereto, the switching mechanism being controlled in various manners by the calling subscriber and the conditioningot the switching mechanism and the character of the ringing current being automatically determined by the character of the called line.

Another feature of the invention consists in the provision of a link circuit connnon to a plurality of lines of different character for extending a call from a relay line finder to a relay connector.

Another feature oi? the invention consists in providing a link circuit tor interconnect.- ing lines in an automatic telephone system, with revertive ringing apparatus within the link circuit itself, no special switches being necessary for handling rcvertive calls.

Another feature of the invention consists otthe provision of means in a system of this nature whereby a link circuit adapts itself automatically for operation as a full metallic or simplex circuit, depending upon the chai acter of the calling line.

Other featuresincluding other circuit details will be more apparent as the descrip tion progresses.

The drawings when placed in the manner indicated in ll diagrammatically illustrate means for carrying out the invention. Figs. 1 to 4; inclusive and Figs. 6, 7 and 9 of the drawings when arranged as shown in Fig. 11 illustrate means for interconnecting lines terminating in the exchange and when arranged as shown in Fig. 11 except with a duplicate of Fig. 7 below Fig. 5, illustrate means for connecting lines of the exchange to an operators position at a distant exchange or vice versa. Fig. 1 includes the circuit arrangement and apparatus for an individual line, a. party line, and a rural line subscribers station. Fig. 2 includes a trunk connector circuit. Fig. 3 includes a subscribers line finder and a subscribers connector circuit. Fig. 4 includes line relay equipment. for the subscribers station shown in Fig. 1, group, subgroup, and units con trolling relays and an allotter circuit. Fig.

5 includes a trunk link circuit. Fig. 6 includes a portion of a subscril'iers link circuit. Fig. 7 includes a set of a counting relays and ringing equipment for rural and party lines. Fig. 8 includes a trunk, circuit extending from the relay automatic exchange to an operators position at a distant exchange and a portion of an operators cord circuit. Fig. 9 includes a portion of a subscribers link circuit. Fig. 10 shows a number and lettering arrangement for an inn-- pulse sender or a dial which is contemplated for use in this system.

The system herein disclosed contemplates an exchange having a capacity of 200 lines although it is to be understood that the in.- vention is not limited to a system of this capacity. The subscribers lines in an exchange having a capacity of 200 lines may be divided into groups of twenty lines each, each group being divided into two subgroups of ten lines each. The invention is equally well adaptable for various other capacities, for example an exchange of one hundred lines may be divided into four groups of twenty five lines each, each group being divided into five sub-groups of five lines each or again, an exchange of three hundred and thirty six lines may be divided into twenty one groups of sixteen lines each, each group being divided'into four subgroups of four lines each, etc. Lines of different character, such as individual lines, party lines, and rural lines may be arranged separately, in groups, or combined together in any manner desired in groups. As shown in Fig. l of the drawings each line has four conductors and the connections for each class of lines at the exchange is iden tical with the exception of connections of the fourth conductor. For individual lines the fourth conductor will be open at the exchange, for party lines the fourth conductor will have a resistance therein, and for rural lines the fourth conductor will be connected directly to ground. It is thus seen that a slight change in this fourth conductor at the exchange is all that is necessary to change subscribers line from one class of service to another.

As herein. disclosed each party line may have four stations thereon although it will be readily apparent to those skilled in the art that the system is adaptable for a greater number than this. Each rural line may have as many stations on the line as is desired. Although in the present disclosure means for ringing three of such stations only has been shown, it will be apparent that the system is readily adaptable for more than this number. It is thus seen that -the system herein disclosed provides for 200 lines and a capacitv for as many stations as cuits, and relay connectors are employed, such apparatus being common to the dlfferent classes of lines.

In general the system functions as fol lows in the case of establishing a connection between two lines of the relay system. In response to the initiation of a call from a line, a group, a subgroup, and a units controlling relay are actuated which cause the actuation of a group, subgroup, and units relay in a preselected line finder, which in turn extends the calling line to a link circuit. For each link circuit there is provided a set of counting relays and impulse recording means which receives the impulses transmitted by the calling line and records them so that a group, a subgroup, and a units relay of the connector circuit corresponding to the number of the desired line are operated and connection is made with the desired line.

Associated with each link circuit are a plurality of sources of code ringing for ringing rural lines, a plurality of sources of different frequencies for ringing party lines, and means for ringing individual lines, together with switching mechanism comprising various relays which operate to connect ringing current to the lines. The relays which connect the ringing current to the lines are controlled in various manners by the calling subscriber, and the conditioning of the link circuit for the application of the ringing current to the line is determined by the character of the called line. For example, it an individual line is called alternating current is automatically applied to the individual lineyif a party line is called, ringing current of a frequency corresponding to the line of the called station is applied to the line in response to the dialing of a letter corresponding to the particular party desired. It is to be noted, however, that the relay connector is associated with the called line before the ringing current is applied, and that no switch is actuated in response to the transmission of the number of impulses corresponding to the letter of the desired station but simply a relay or a set of relays actuated to connect the proper frequency with the called line.

A two-way trunk circuit is also provided by means of which calls may be made to or from any station of the exchange to a distant exchange. 011 outgoing calls from a station to a distant exchange the calling subscribers line relay is actuated, which causes the operation of a particular group, subgroup, and units relay, which in operating cause the operation of relays in a relay line finder and the connection of the calling line with the link circuit. The calling subscriber then dials, causing ten impulses to be sent, in response to which the counting relays and impulse recording means cause sired subscriber.

the relay connector to be actuated, whereupon a group, a subgroup, and a units relay therein, actuate to connect with the calling line. The line finder relays are thereupon disconnected from the calling line and the calling line is extended to the trunk circuit. Ringing current is then automatically applied to the trunkcircuit extending to this exchange which causes the actuation of a signal at the distant exchange. The trunk circuit is automatically adapted for simplex or full metallic operation depending upon the character of the line at the exchange to or from which the call is extended.

On an incoming call from the distant exchange the operator at said distant exchange inserts the calling plug of one 01 her cord circuits into the jack of the trunk circuit and then proceeds to actuate her dial a number of times corresponding to the number desired at the relay automatic exchange. In response to the impulses transmitted over the trunk line, the set of counting relays and the impulse recording device shown in Figs. 5 and 7 of the drawings will be actuated to cause the operation of a set of trunk connecting relays, such as shown in Fig. 2, to extend the trunk to the line of the desired subscriber. If the station of an individual line is desired, alternating current will be automatically applied to the line of the de- It a rural or a party line subscriber is desired the operator will actuate her impulse sender to send a set of impulses corresponding to the letter oi the desired subscriber, whereupon either code ringing current or frequency ringing current will be applied to the line of the desired subscriber in a manner similar to that for a subscriber to subscriber connection. The trunk circuit is conditioned for the application of the proper source of ringing current thereto for signalling the called subscriber by an electromagnetic means which does or does not operate depending on the character of the called line.

UaZZ from 03 party Zinc station to (6 station on the same Zine.

Let it be assumed that station L or a party line 312 desires a connection with the station M on the same line. Upon the removal of the receiver 156 from the switchhook 158, line relay 4A2 individual to the calling line, is energized over a path extending from grounded battery, upper winding of relay 442, back contact and outer armature of cut-oft relay 470, primary winding of induction coil 155, contacts 159, receiver switchhook 158, transmitter 15 contacts 151 of sender S1, inner armature and back contact of relay 470 and lower winding of relay 4-12 to ground. Subgroup relay 431, units relay U2 and relay AD thereupon energize over a path extending from ground, letthand armature and back contact of relay 1:00, winding of relay 431, arnjiature and 1.. int contact oil relay 4A2, winding oLt relay U52 and winding of relay AD to grounded battery. Group relay ltiei 'w is thereupon energised over a path extending from ground, left-hand armature and bacl; contact of relay 4'10, lower miniature and back contact of relay 41:05, right-hand armature and back contact of relay 41-32, right-hand arniati'ire and Front contact of relay 131 and right-hand winding of relay 464 to grounded battery. Relay 4-04: then completes a locking circuit for itsel'l and an energizing circuit for relay 4-05 over a pa h extending from grounded battery, left-hand winding, front Contact and inner lett-hr id armature or" relay 464i. winding of re 405 and back contact and leftdiand armature of relay 410 to ground. Relay thereupon operates and completes a circuit for slow-to-releasc relay 406 over a path extending from ground, upper armature and front contact of relay 405, left-hand armature and back contact of relay 4-0? and winding of relay 4100 to grounded battery. Relay 400 in operating completes a circuit for operating relay 407 over a path extend ing from grounded battery, winding of relay 407, front contact anc armatureof relay 40c and front contact and upper armature of relay 405 to ground. Relay 407, in attracting its left-hand armature. opens the energizing circuit for slow-to-release relay 4:06 where-upon said reay 4.00 releases. As 3% soon as relay 400 retracts its armature a cir cult is completed for slow-to-release starting relay 408 over a path extending from ground, upper armature and front contact of relay 405, armature and back contact of 105 relay 4-06, front contact and rightdiand armature of relay 407 and winding of relay 408 to grounded battery. The purpose of slow-to-release relay 4:06 and relay 1-07 is to delay the operation of the starting relay 408 no in the event that two calls come in at the same time, thereby providing a time interval during which the group and sub-group rclays, of those group circuits, which have not obtained connections with the starting cir cuit, can fully release and thus insure that their contacts will be opened, and that but one groin) circuit is connected to the starting circuit at that time.

i i hen the starting relay 4:08 operates, no ground is extended through the armature and front contact of relay 408, rightehand armature and back contact of relay 410, brush 15 and contact 416 of switch FS, conductor F1, left-hand armature and back contact of relay 303 and winding of allotter relay 310 to grounded battery.

Switch F5: is (it that type in wuicli no normal position is provided. Hence its brush rests on the contact to which it was last no moved. In the present case it is shown as battery, winding of relay 310, front contact;

and innermost right-hand armature of relay 310 winding of relay 410, front contact and armature of relay 108 to ground. Relay 410 does not operate at this time as it is short circuited by the original energizing ground connection for relay 310. Allotter relay 310 V in operating indicates that line finder LFl has been allotted and the circuits of the group, subgroup and units relays of this line finder are closed to the starting circuit. Group rela 362 of the line finder LFl is operated over a path extending from grounded battery, winding of relay 362, contacts 363 of relay 31.0, and right-hand armature and front contact of group relay 464C to ground. Sub-group relay 300 of the line finder LE1 is operated over a path extending from grounded. battery, winding of re lay 300, contacts 321 of relay 310, front contact and left-hand armature of sub-group relay 431 to ground. Units relay 302 of the line finder Ll l is operated over a path extending from grounded battery, winding of relay 302, contacts 365 of relay 310. and front contact and armature of relay U2 to ground. Group relay 362, sub-group relay 300 and units relay 302 are thereupon locked up in parallel to ground at the contacts 350 of relay 310.

The line of the calling station is thereby extended through to the link circuit. Relay 901 of the link circuit is then operated over a path extending from grounded battery, winding of relay 901, back contact and lower armature of relay 904:, lower righthand winding of repeating coil 910, back contact and inner right-hand armature of relay 911, conductor C2, contacts 371 of relay 302, contacts 372 of relay 300. contacts 376 of'relay 362, contacts 151 of impulse sender S1, transmitter 154, switchhook 158, contacts 159, primary winding of induction coil 155, contacts 377 of relay 362, contacts 378 of relay 300, contacts 370 of relay 302, conductor C1, outer right-hand armature and back .contact of relay 911, upper righthand winding of repeating coil 910, upper inner armature and back contact of relay 904; to ground.

The line of the calling party has a resistance 492 connected in the fourth conductor and relay 903 of the link circuit is therefore not operated, since the resistance is of such a value as to prevent the opera tion of this relay when the calling line is extended through to the link circuit. Relay 902, however, not being marginal as is relay 903 does operate, being energized in a circuit extending from ground resistance 492 innermostleft-hand armature and front contact of relay 362,'next to the lowermost armature and contact of relay 300, innerinost left-luu1d armature and front contact of rela 302, conductor L; winding of relay 903, winding of relay 902 to battery and ground. The operation of relay 902 removes a ground connection from the lower winding of relay 620 whereby the first set of impulses is effective to energize the STA relay as will hereinafter appear. Impulse relay 901 in operating completes a circuit for slow-to-release relay 906 over a path extending from ground, armature and front contact of relay 901 and winding of relay 906 to grounded battery. Slow-to-release re ay 906 thereupon operates and completes a circuit for the energization ofthe cut-off relay 470 of the calling line and relay 303 of the line finder LE1 over a path extending from ground, winding of cut-0E relay 170, contacts 37 1 of group relay 362, con tacts 333 of sub-group relay 300, contacts 381 of units relay 302, conductor S, lefthand armature and front contact of slow-torelease relay 906, conductor AS, and windlay AD. Relay 303 in attracting its left hand armature opens the starting circuit to the allotter relay 310.

Opening of the'starting circuit at the lefthand armature and back contact of relay 303 removes the short-circuit from relay 410 whereupon relay 410 operates, and relay 310 is held energized in series with the winding of relay 410. As soon as relay 303 operates, the starting wire although open at the back contact of relay 410 is extended to the next allotter relay (not shown) thereby preventing two finders from making connection with the calling line and insuring that another finder circuit is ready for selection. As soon as relay 110 operates it opens the holding circuit for relays 05 and 464.. Relay 405 in retracting its upper armature opens the circuit forrelay 4:07 causing the release of said relay 107 whereupon the circuit for slow-to-release relay 408 is opened. Relay 103 being of the slow-to-release type does not retract its armature until a short interval after its energizing circuit is inter rupted thereby giving sufficient time for the release of all relays of the group and starting circuits, and at the same time holding the allotter relay of the finder circuit busy. When relay 4110 operates, a circuit is closed for the operation of the stepping magnet 412 over a path extending from ground, lefthand armature and front contact of relay 410, back contact, armature and winding of magnet 412, resistance 461 to grounded battery. Relay 411 energized in parallel with stepping magnet 412 and in attracting its right hand armature places ground on the windiin of stepping magnet 412 to insure a complete step of the brush 415 controlled by the magnet.

The action of the time-interval relays should be noted at this point. When the line relay first is energized, it causes the cnergization of relays 431, 464, U2 and AD. 'lhe-reupon a circuit is closed from ground, the armature and front contact of relay AD, lowermost armature and back contact of relay 468, winding of relay 413 to battery and ground. Relay 413 closes a circuit through its armature and front contact "for the energization of relay 414, which in turn closes a similar circuit through its armature and front contact for the energization of relay 468. Relay 468 locks up through its innermost lower armature and front contact to the ground at the back contact and left-hand armature of relay 411. The movement of the armatures of relay 468 opens the energizing circuit of relay 413. In a short interval, relay 4 13 becomes deenergized, whereupon the energizing circuit for relay 414 is opened and after an other short interval relay 414 deenergizes. ln the mean time, however, and under normal operating conditions, relay AI) will have become dcei'iergized since immediately upon the energization of relays 431, 464 and U2, the calling line is connected to the link circuit and relay 9.00 is energized causing, as hereinl'iel o-re described the energization of the cut-oil relay 470. The energization of the cut-oil relay in turn causes the deenergizatiou of those relays controlled by the line relay and therefore relay AD becomes deenergized. Also the original energizing circuit for relay 310 is opened at this time, due to the energization of relay 303 by relay 906, whereupon relay 410 becomes energized as hereinbefore described. Simultaneously with the energization of relay 410, the energizing circuit of relay 408 is opened but relay 405%, being slow to release, main tains the circuit for relay 410 closed for a short time-interval. During this time interval, relay 411 energized, whereupon the ina 'net 412 is energized so that the brush 415 will be moved onto its next contact and the locking circuit for relay 468 is opened by the movement of the armatures oi relay 4-11.

it there is any delay in the operation of the allotter relay 310 then an automatic operation of the brush 415 will take place. lfi upposc for instance, there had been a dirty contact between the brush 415 and its contact 416, then upon the energization of relay 408 none of the group, sub-group or units relays such as 362, 300, and 302 would have been energized because relay 310 could not be energized and the line circuit would not have been extended to the link circuit. The relays 413, 414 and 468 would thereupon go through the actions described, but relay 468 would not become deenergized due to the breaking of its locking circuit by relay 41.1. ()n the other hand relay AD would have remained energized for much longer period than usual; hence upon the deenergization of relay 414, a circuit is established from the ground on the armature andiront contact of relay AD, the armature and back contact of relay 414, the front contact and upper armature of relay 4 8, the back contact and-armature of magnet 412, winding of magnet 412, resistance 461 to battery and ground. The brush 415 will then be moved to its next contact 417. In parallel with the winding of magnet 412, relay 411 will be energized, thereby breaking the locking circuit of relay 4G8 and opening the circuits of magnet 412 and relay 411. Thereupon relay 413 will become energized again and unless the allotter relay for the next finder is operated as hereinbefore described, this same action wil. t he place resulting in the further movement of brush 415.

Under the control of the impulse sender S1 at the station of the calling subscriber. the impulse relay 901 of the link circuit will be actuated a number of times to cause the extension of the line of the calling subscriber to the line of the called subscriber. As hereinbefore stated, when a station on a party line calls another station on the same line, the calling subscriber first dials the sullix of his station and then dials the number of the desired station. t having been assumed that the party L of: the party line desires connection with a party it? on the same line, he will, as will be noted by referring to Fig. 10 of the drawings, first dial the letter L, causing six impulses to be transmitted to the impulse relay 001 of the link circuit. The calling party will then dial the digits 3, 1 and 2 and thereafter the letter, M. In dialing the letter M it will be noted, by referring to F 10 of the drawing, that seven impulses will be transmitted to the impulse relay 901.

It should be noted at this point that the impulse senders S, S1 and S2 are arrange-(l to send impulses which are, as a ma ter of fact, interruptions of the circuit rather than impulses. However, those skilled in the art commonly speak of a series of interruptions in this type of circuit as a series of impulses, and since this is now common practice, this terminology will be maintained throughout this specification.

ii! an,

Hereinafter when an impulse or a series or train of impulses is spoken of as being sent from a supstation dial it will be understood that an interruption of the circuit of very short time duration is meant.

In response to the first impulse of the first series transmitted to the impulse relay 901, relay 702 and counting relay AP Will be energized over a path extending from ground, armature and back contact of relay 901, armature and back contact of relay 905, front contact and right-hand armature of relay 906, conductor ST, outer left-hand armature and back contact of relay 740, and thence in parallel, one path extending through the Winding of relay 7 O2 to grounded battery, and the other path extending through the right-hand armature and back contacts of relays D, C, B, and A. and the Winding of relay AP to grounded battery. Relay 702 in operating completes a circuit for the energization of relay 740 over a path extending from grounded battery, Winding of relay 7 410, front contact and left-hand armature of relay 702, conductor H, and outer right-hand armature and front contact of relay 303 to ground. Relay 7 40 in operating locks up through its front contact and inner left-hand armature, the armature and back contact of relay 741 to ground on the holding conductor H. The impulse circuit over the conductor ST is noW closed through the front contact and right-hand armature of relay 702 and opened at the outer lefthand armature and back contact of relay 7 10. Relay AP in operating prepares a circuit for the operation of relay A over a path extending from grounded battery, Winding, armature and front contact of relay AP, Winding of relay A, back contact and left-hand armature of relay B, front contact and inner left-hand armature of relay 740, armature and back contact of relay 741 to ground on conductor H. Relay A Will not operate over this circuit, however, until the impulse relay 901 attracts its armature at the end of the first impulse. As soon as the first impulse is completed and relay 901' attracts its armature, relay A operates due to the momentary removal of ground from conductor ST, thereby connecting the counting relay BPin circuit with the conductor ST. In response to the second impulse transmitted to the impulse relay 901, counting relay BP is energized over a path extending from ground, armature and back contact of relay 901, arma ture and back contact of relay 905, front contact and right-hand armature of relay 906, conductor ST, front contact and righthand armature of relay 702, right-hand contacts of relays D, C, B, and right-hand armature and front contact of relay A through the Winding of relay BP to grounded battery. Relay BP in operating prepares a circuit for the counting relay B over a path. extending from grounded battery, Winding, armature and front contact of relay Bl Winding of relay B, back contact and lefthand armature of relay C, front contact andinner left-hand armature of relay 7&0, and armature and back contact of relay 741 to ground on conductor H. As soon as relay 901 attracts its armature at the end ofthc second impulse, relay B operates and relays BP and B lock up over a path extending from grounded battery, Winding, armature and front contact of relay BP, Winding of relay B, back contact and left-hand armature of relay 0, front contact and inner lefthand armature of relay 740, armature and back contact of relay 7 11 to ground on conductor H. Relay B in operating opens the locking circuit for relays AP and A, Whereupon they release.

At the third interruption of the line cir cuit, counting relay GP Will be operated over a path extending from ground, armature and back contact of relay 901, armature and back contact of relay 905, front contact and right-hand armature of relay 906, conductor ST, front contact and right hand armature of relay 702, through the right-hand contacts of relays D and C, right-hand armature and front contact of relay B, and Winding of relay GP to grounded battery. Belay GP in operating prepares a circuit for the energization of relay C over a path extending from grounded battery, Winding armature and front'contact of relay GP, Winding of relay C, back contact and outer left hand armature of relay D, front contact and inner left-hand armature of relay 740, armature and back contact of relay 74-1 to ground on conductor H. As soon as relay 901 attracts its armature at the end of the third impulse, relay 0 energizes, whereupon relays GP and C lock up over a path extending from grounded battery, Winding of relay GP, armature and front contact of relay GP Winding of relay C, back contact and outer left-hand armature of relay 1), front contact and inner left-hand armature of relay 740, armature and back contact of relay 7 41 to ground on conductor H. Relay C in operating opens the locking circuit for relays B and BP, whereupon said relays release.

At the fourth interruption of the relay 901, counting relay DP is energized over a path extending from ground, armature and back contact of relay 901, armature and back contact of relay 905, front contact and right-hand armature of relay 906, conductor ST, front contact and right-hand armature of relay 702, right-hand armature and back contact of relay D, right-hand armature and front contact of relay C, and Winding of relay DP to grounded battery. Relay DP thereupon operates and prepares a circuit for the energization of relay D over a path extending from grounded battery, Winding, armature and front contact of relay Dl winding of relay D, back contact and left-hand armature of relay A, front contact and inner left-hand armature of re lay 740, armature and back contact of relay 74:1 to ground on conductor H. Relay D Will not operate until relay 901 attracts its armature at the end of the fourth impulse. As soon as relay 901 attracts its armature, relay D operates and relays DP and D lock up over a path extending from grounded battery, winding, armature and front contact of relay DP, winding of relay D, back contact and left-hand arniature of relay it,

front contact and inner left-hand arinature of relay 740, armature and back contact of relay 741 to ground on conductor H. Relay D in operating interrupts the locking circuit for relays C and GP, whereupon said relays release. As soon as relay D operates, relay CTP will be operated over a path extending from grounded battery, winding of relay CTP, hack contact and outer righthand armature of relay CT, front contact and outer left-hand armature of relay D, front contact and inner left-hand armature of relay 740, armature and back contact of relay 741 to ground on conductor H. Relay CTP in operating locks up in series with relay CT.

In response to the fifth interruption of the line circuit, relay AP will be operated over a path extending from groui'id, arrnatuhes and back contacts of relays 901 and 905,

front contact and right-hand armature of relay 906, conductor ST, front contact and right-hand armature of relay 7 02, righthand arn'iature and front contact of relay D, and winding of relay AP to grounded battery. Relay AP in operating prepares circuit for relay A over a path extending from grounded battery, winding, arniature and front contact of relay All winding of relay A, back contact and lefthand arnialure of relay B, front contact and inner left-hand armature of relay 740, armature and back contact of relay 74-1 to ground on conductor H. hen relay 901 attracts its armature at the end of the fifth interruption of the line circuit, relay A operates. Relays AP and A then look up over a path previously traced. Relay A in operating interrupts the locking circuit for relays DP and D. When relay D releases, the shunt around the winding of relay CT is removed and this relay becomes energized in the locking circuit of relay CTP.

At the sixth interruption of the line circuit. relay BP is operated over a path extending from ground, armature and back contact of relay 901, armature and back contact of relay 905, front contact and righthand armature of relay 906, conductor ST front contact and right-hand armature of relay 7 02, right-hand armature and back contact of relay D, right-hand armature and back contact of relay C, right-hand arinature and back contact of relay l3, right-hand armature and front contact of relay A, and winding of relay BP to grounded battery. Relay HP in operating prepares a circuit for the operation of relay ll over a path previously traced. When the relay 001 attracts its armature at the end of the sixth impulse, relay B operates and relays B1 and B thereupon lock up over a path previously traced. Relay B in attracting its armature opens the holding circuit for relays A {UK A? whereupon said relays release.

A short interval after the end of the sixth intenuption of the line circuit, slow-to-release relay 702 retracts its armature, thereby completing a circuit for relay 600 over a path extending from ground, front contact and outer right-hand armature of relay 303, conductor H, left-hand armature and back contact of relay 702, front contact and outer right-hand arinature of relay 7 10, conductor l lower armature and back contact of relay 620, and winding of relay 600 to grounded battery. The contacts of the counting relays FT, C'l, FTP and CTP, shown in Fig. 7 of the drawings, are connected with the relays 000 to 004- inclusive, and A l, shown in Fig. 6 of the drawings, indicated by the similar numbers.

As soon as relay 000 operates, the rinrelay 612 is energized over a path entenc froi'n grounded battery, wind 'iq' of relay upper inner arinatur and front con tact of relay 600, and thence by a connection, not shown), to the l aclr contact and inner right-hand a: -iature of counting re lay FT, front contact and inner right-hand armature of relay CT, front contact and inner left-hand armature of relay B, int contact .d inner left-hand arn'iature or. relay 740, armature and back contact of relay 74-1 to ground on COIUlUCLOT H. Relay (310 in operating locks up in series with relay 620, over a path extending from grounded battery, winding and front contact and lower inner armature of relay 012, upper Winding of relay 020 to ground on conductor H. Relay 612 in operating completes a circuit for the operation of relay 741 over a path extending from ground on. conductor H, lower outer armature and front contact of relay 612, lower outer armature and. n nt contact of relay 600, conductor inner right-h and a ran atu and nont Contact of relay 74:0. and windine' oi' relay 7451 to grounded battery. Belay 74-1 in operating response to the dialin ofthe digit 3 impulse relay 901 will he deenergized three times. At the first deenergizaation of relay 9 01 sloW-to-release relay 702 and counting relay AP Will be energized in a manner herebefore described. lilclay 702 in operat ing causes the operation of relay 740, which look. to ground conductor ll. Nhcn the relay 901 attracts its armature at the end of the first interruption, counting relay A operates, whereiuiion relays Al and A lock up to ground on conductor ll. At the second interruption of the line circuit, relay 901 in retracting its armature, completes an ener 'iring circuit for relay Bl Relay Bl. in operating prepares a circuit for the energization of counting relay B. li hen relay 901 attracts its :11 nature at the end of the second interruption of the line circuit, relay l) operates and relays Bi and B then lock up in series to ground on conductor l-i. Relay B in operating opens the locking circuit for relays AP and A, whereupon said relays release. At the third interruption of the line circuit relay 901 in retracting its armature completes a circuit for the opera tion of relay GP. Relay GP in operating prepares a circuit for the energization of relay C. When relay 901 attracts its armature at the end of the third interruption of the line circuit, relay (l operates, Whereupon relays Cl. and C loch up in series to ground on conductor ll. llelay (l in operating releases relays El and B,

After the third impulse has been delivered to the impulse relay 901, the line circuit will be closed for a relatively long interval, whereupon slow-to-release relay 702 will release, hereby completing a circuit for the energization of relay 601 over a path extending from ground, front contact and outer right-hand armature of relay 303, conductor H, left-hand armature and back contact of relay 702, front contact and outer right-hand armature of relay 740, conductor l ari'i'iature and front contact of relay 620, armature and back contact of relay 621, and Winding of relay 601 to grounded battery.

Relay 601 thereuponoperates and completes a circuit for the subgroup connecting relay 896 over a path extending from grounded battery, Winding of relay 396, upper intermediate armature and front con tact of relay 601, and thence by a connec tion, (not shown), to the like numbered contact of counting relay GT1 front con tact and left-hand armature of relay C, front contact and inner left-hand armature of relay 74-0, arn'iature and bacl: contact of relay 741, conductor H, and outer right-hand armature and front contact of relay 303 to ground. Relay 096 in operating locks up over a path extending from grounded battery, Winding, front contact and upper armature of relay 396, Winding of relay 621 to ground on conductor ll. Relay 621 is energized and locked up in the circuit ust traced, thereby transferring the conductor ll to the tens relay 602. Relay 396 in operating completes a circuit for reverting busy test relay 358 over a path extending from grounded batter Winding of relay 358, contacts 3o7 of relay 396, upper contacts of relay 300 and contacts 350 of relay 310 to ground. Relay 601 in operating also completes a circuit for the energization of relay 7 11 over a path extending freer grounded battery, Winding of relay 741, front contact and inner right-hand armature of relay 740, conductor E, front contact and lower inner armature of relay 601, lowermost contacts of relay 396, and outer right-hand armature and front contact of relay 303 to ground. Relay 741 in operating opens the holding circuit for relay 7t0, Which releases thereby opening the holding circuits for the counting relays C and GP, Which in turn release. Relay 740 in deenergizing releases relay 741.

In response to the next interruption of the line circuit in dialing the digit 1, relay 901 retracts its armature and completes a circuit for sloW-to-release relay 702 and counting relay AP. Relay 702 in operating completes a circuit for the operation of relay 7 40, which looks up to ground on conductor ll. Relay AP in operating prepares a circuit for the operation of relay A. When relay 901 attracts its armature at the end of the impulse, counting relay A operates, Where upon relays AP and A lock up in series to ground on conductor H. At the end of the transmission of this impulse, the line circuit is closed for a relatively long interval of time, whereupon slow-to-release relay 702 releases, thereby completing a circuit forthe energization of tens relay 602 over a path extending from grounded battery, Winding of relay 602, back contact and lower armature of relay 622, front contacts and armatures of relays621, and 620, conductor F, outer right-hand armature and front contact of relay 740, back contact and left-hand armature of relay 702, conductor H, and outer right-hand armature and front contact of relay 303 to ground. Relay 602 in operating completes a circuit for the group connecting relay 397 over a path extending from grounded battery, Winding of relay 397, upper inner armature and front contact of relay 602, and thence over a connection, not shown, to a like numbered contact of count-- ing relay CT, front contact and left-hand armature of counting relay A, front contact and inner left-hand armature of relay 74:0, armature and back contact of relay 741, conductor H, outer right-hand armature and front contact of relay 303 to ground. Relay 397 in operating locks up over a path extend- M1 in 71:, .e M H V curt l. 1 rela Mir 2 ing from grounoetl battery, Winding, Front contact and i'l;3;lii-'ii2a1i(l minim o'i rela I 1 clay 622 to e ouni'l on conductor r.

622 ener, see and lock? c U up 111 series W1 1 lQlLrj' over the circin just traced. lielay 39? in operating coilipletes a circuit lot: reverting sy test relay 351 Sillil circuit including contacts o't relay 897, 362 antl 310. y 02 in operatin also completes a circuit ilor the ene" '1.z ition.

of relay 741 over a path extencli 1g from grounded battery, winding of relay Yell,

front contact anc inner r ght-hano arr'iiatur of relay 7&0, conductor E, tl ront contact and r 1 H 1 I V W 0 lower armature or relay e02, l/llltifiltr; 09%) i; l -hanrl armature lay 2303 to grouno.

s and in attractfor co saicl r counting relay circu reception of the :11

impulse to the impulse release relay 702 and gizcclv Belay 1202 in operoircuit for the of: relay 4") Which. operates and locks up to groun'l on conductor l'l. l in opcrat" pires a circuit counting relay n. rclay 901 attracts its of the first ii' I i operates, wheicripon I up through the front c n honcl arinat o'l l W hen inatue at the cnrl conductor ll. pulse this s-e.1e ooerates over a oatn pre; i prepares a circ ut r t :rguzxa counting relay l3 'li hen relay 901 a 4 l'l'S armature at the entl oi" the second impulse of the units series of nnpulses, relay oper ates whereupon relays El and lock up over a path previously traced ground on conductor Relay B in operating opens L1 1 1-; 'i-

31111,,1 {r i re ocalng cocci-c or ii (LAC ll vhereupoi. saicl relays A. aucl AP releei-ze he on n trans-- rr ter the units impulses have No lUl'i tBCl, the line circuit will he closed, for a relatively long iner ml of time, \TlKlPH' 'JOH slow-to-release r lay releases thereby causing the onergizzction of units relay 03 over a path extending from grounded ba e tery, Winding of relay 603, back contact and armature of relay 623, front contacts and erniatures of relays 622, 621, and 620, contluctor l outer right-hand. armature and front contact of relay 74:0, bacl: contact ancl leltthanrl arm? "ure of relay T02, conductor ght-han l arj mtnre and front a to ground. Units relay 603 in operating completes a inner left-hand art. iture of relay 740, armantl hack contact of relay 7 conductor Kl outer right-l and armatu'c and front oatact of relay 3 to ground. Units re 8 in operating locks up over a path ex front contact from grounflec o c of re ling of relay ane conouctor 1 at the rightl'lfifld armature and t ntact of rela 0 V r r I. m3. nelay ener niotainerl relay 603 in operating also comfor relay 920 of the link circult over a path eltending fr in grounded li attery wiruling oi relay 920, uppermost armature and front contact of relay to ground. llelay 920 ot the link circuit in operating completes e test circuit extending 'oin wound on conductor ll, Winding and left-l (l normal contacts mi relay 921, front contact and armature of relay 920, and thence through the sleeve contacts of relays 898, 3% and 397 to the sleeve conductor of line Battery potential being present on the sleeve conductor, since the calling line is being called, relay 921 01 crates and locks p through its left-hand alternate contacts. l hen the units connecting relay 398 energized it completed a circuit for the energization of the reverting busy test relay 369 yer a path extending from grounded battery Winding of relay 359, inner loin-hand armature and front contact of relay 398, front cor tact and rig t-haul armature oi ry intermediate right-hand ar inacure ano front contact of relay 310 to ground.

As soon as the last innoulse the units cries of irnonso was (leliv i 5 co to the im- 1 so relay 901 one relay its released, relay l opeivte r a path extending :lrorn grounded lia' ry, Wino 'l ront contact anil inner right-han-il armature of rel? 74:0, coiitluctor Fl, front connect 21ml. 1* (303, contacts 0v e of: relay n21,

lower most arniiature ol ol relay 398, and outer right-ha i le -730 3170 round,

h l lo chi n g ses o} coun g rela "Z40 in releasing releases ll clay The counting relays are thereupon restored to normal and ready for the next set of imulses.

As soon as relay 623 operated, units relay 603 released, thereby causing the release of sloW-to-release relay 920 of the link circuit.

'After dialing the units impulses the calling subscriber dials the letter corresponding to-the station of the desired subscriber. At the first interruption of the line circuit in response to the dialing of this series of impulses, sloW to release relay 702 and counting relay AP are energized? Relay 702 in operating completes a circuit for the energize.- tion of relay 7&0 which in operating locks up to ground on conductor H. Relay AP in operating prepares a circuit for the energization of counting relay A. When the inipulse relay 901 attracts its armature at the end of the first impulse of this series, counting relay A operates whereupon relays Al and A look up to ground on conductor H. In response to the second impulse of the series transmitted to the impulse relay 901, counting relays El and B will be energized. These relays then look up to ground on conductor H. Relay B in operating opens the locking circuit for relays AP and A. in response to the third impulse of this series, relays CP and G are operated and then lock up to ground on conductor H. Relay C in operating opens the locking circuit for relays BP and B, which thereupon release. In response to the fourth impulse of this series transmitted to impulse relay 901, relays DP and D operate and lock up to ground on conductor Relay D in operating opens the locking circuit for relay GP and C, whereupon said relays release. llelay D in operating completes an energizing circuit for relay DTP, and is held operated through ground on conductor H. in response to the fifth impulse of this series transmitted to the impulse relay 901, counting relays AP and A are again energized and in operating lock up to ground on conductor H. Relay A in operating opens the locking circuits for relays DP and D, whereupon said relays release and the counting relay CT operates and locks up in series with relay Cll In response to the sixth impulse transmitted to impulse relay 901, counting relays DP and B are energized and in operating lock up to ground on conductor ll. Relay D in operating opens the locking circuit for relays Al and A. In response to the seventh impulse transmitted to the relay 901., relays Cl and C operate and thereupon lock up to ground on conductor l-l. Relay C in operating opens the locking circuit for relays El? and B, whereupon said relays release.

At the end of the last series of impulses, impulse relay 901 retains its armature attracted, thereby causing the release of slow- 'to-release relay 702. Relay 702 in retracting its armature completes a circuit for the energization of relay 6% over path extending from grounded battery, winding of relay 004-, back contact and lower armature of relay 624, front contacts and armatures of relays 623,, 022, 621 and 620, conductor F, outer right-hand armature and front contact of relay 7 e0. bacl: contact and left-hand armature of relay 703.5, conductor H, and outer right liand armature and front contact of relayZ-EOS to ground. llelay 004: in operating completes a circuit for the energiz-ation of relay 6231 over a path extending from grounded batte winding of relay (ii-ll, uppermost armat re and front contact of relay 001,. and thence orer a connection, not shown, to a like numbered contact of counting relay FTP, front contact and outer right-hand armature of relay CTP, front contact and left-hand armature of relay Q, front contact and inner left-hand armature of relay 7 i0, arn'iature and baclr contact of relay 1, conductor ll, and outer right-hand armature and front contact relay 303 to ground. Relay 631 in operating completes a locking circuit for itself over a path extending from grounded battery, winding of relay 031, upper inner armature and front Contact of relay 631, winding of relay 6%, conductor ll, outer right hand armature and front contact of relay 303 to ground. Relay 624 is energized and maintained operated in series with relay 681 over the circuit just traced. Before relay 02 1 is operated however. relay 7&1 is operated over a path extending from grounded battery, winding of relay 741, front contact and inner right-hand armature of relay 7 l0, conductor l9, front contact and lower armature of relay 004:, front contact and upper armature of relay conductor ll, "front contact and outer right-hand armature of relay 803 to ground. l tela 742-1 in operating opens the locking circuit for relay 740 which thereupon releases. llelay 740 in re leasing opens the holding circuit for the operated relays of the counting circuit. and the operating circuit for relay 7431, whereupon said relays r restored to normal.

Upon the cue cult is closed I and armature of rarmature and front contact of relay 358, armature and front contact of relay 359. uppermost armature and front contact of relay 631. to the wii'idings of relays 930 and 931 in parallel to battery and ground. llelays 930 and 931 are energized in this circuit. Relay 931 closes a circuit for the energization of relay which extends from i attery, winding of relay 932, front contact and left-hand armature of relay 931, front contact and outer right-hand armature of relay 92]., back conout contact ii romeo 3.11?

tact and armature t relay 920. sleeve conductor ol' the callei'l line, contact 894; ct rclay 398. contact 386 ot relay 2-39, contact 87 of relay 397, winding of relay no to ground. It should be noted th relay 4574) has already been cner 'izcd in series with relay o but relay 932 is sensitive and hecomes energized in the circuit just traced.

The energization of relay causes the energization 0t relay 92-12 by means ot a circuit extend inrtroin grounded bat "y winrh ing of relay 922., resistance 940. trout contact and armature of relay 932 to ground. Through the energization o1"? relays 9 2 and 930, a circuit is closed from ground, armature and trout contact of relcy 901. inner lower armature and front contact ot' relay 930, right-hand winding; ot relay 911, back contact and right-hand mature of relay 923. front contact and innermost lower armature ot' relay 922 to the ground on con. ductor H. The cuer rization of relay 9 prevents the ener; nation ot the rii'i 'ing relay 9% at this time so that the calling suhscriber will not hare ringing .iu'rent put 0 the line until he replaces his receiver on I hook.

The subscriber new replaces is on its switchhook for purpose of ringin the calling subscriber. Relay i'esp.'ids by retracting its armature. whereupon a circuit is established "from ground on conductor .l'l through the innermost lower armature and front contact oi? relay 922. the right-hand armature and hack contact ot relay 928. the right-hand winding oil relay 911, the Front contact and innermost ariuature of relay 980. the winding ot rela 906 to battery and ground. Relay 9'l1 becomes energized in this circuit and relay 906 re mains energized to hold the connection. llelay 911 cuts otl the calling; end of the linl: circuit from the repeating coil 910 and thereby removes the relay 901 from the control by the calling subscriber. Through its left-hand armature relay 911 closes a circuit from ground on conductor ll, the innern'iostlower armature and trout contact of rehacl; contact oi":

relay the back contr armature of relay the tr left-hand armature oi 911. relay 9% to battery and ground.

Ringing current will now be transmitted alternately to the stations of the calling and the called subscriber and will he continued until either the calling or the called uh the swi tch- As soon as the called subscriber rcmoves the receiver from the switchhook, the calling subscriber may do likewise. whereupon co yersation may progress. The path of' the current for signaling the called subscriber may be traced as tollows:-ground, source 781 of cycle ringing current, in-

scriber removes the receiver fro? terrupter 791, inner lower armature and front contact of relay Gill. outer armature and trout contr zct oi relay 32:3, trout contact and left-hand arn'iaturo of relay 949i, winding of relay 935, trout contact and uppeu most armature of relay 92%, upper armature and front contact oi relay 9: 32, contacts 395 of relay 398. contacts 583 of relay 396, contacts 375 of relay 397 through the 313 cycle ringer and condenser (not shown) at the called substation hill, contacts 3553 of re lay 397', contacts ot relay 3316 contacts 393 of relay 39c. trout contact and lowerniost armature or relay lor-reruiost' armature and trout contact of relay 92 5 righthand armature and trout contact oi relay 9 51, front contact and inner armature of relay 625, front contact and lower intcrmediate aru'iaturc of relay ii-ll to source or ringing current 781. The path for signalringing current. interrupter 790. u iperinost armature and trout coiuiuot o't relay G12, outer armature a trout contact. of relay G27. trout contact and outer arn'iature otrelay 626 and thence throi'igrh the trout contact and left-hand armature of relay ll ll over the path previously traced through the cycle ringer l53 and condenser li at the calling substation 312 I, through the righthand armature and trout contact of relay 941 inner armature and trout contact of re lay 626, front coiu'iaot and intermediate armature of relay 62?, front contact and up per intermediate zuuiature of relay 619, to source of ringing; current 780. nelay 626 which controls the application of ringing current to the calling line is it.

grounded battery,

(327, trout contact and inner upper armature f; clay 612. and interrupter in.) o gzrounail.

icetion of is inter A extending from grounded buttery windin of relay front contact 211 low ost armature of relay 631 and interrupter (61 to ground. The interrupters F60 and 7 may be so ar ranged that the i and 69.6 are alternately ei'ieru ized so that only one or ringing; current is applied to the line at the some time.

ll l en the .allec subscriber removes the receiver from the switchhoolr, relay 935 will operate due to an increased flow oi? current therethrougn. Relay in operating conipletes a circuit for the energization ot' relay 923 over a path ex ending from ground conductor H, inner lower armature and front contact of relay 922, winding of relay 923, front contact and left-hand armature of relay 911 and winding of relay 92s to grounded elay 625 which controls the uppl ringing current to the called l' e nnttently energized our a n"- fill 

